In addition to the classic probe application areas of cortical, deep structures, peripheral nerve and neural prostheses, there is also interest in using the probes to record from other areas including cardiac muscle and tissue slices. Cardiac muscle, as with peripheral nerve, is a challenging preparation for silicon probes in that penetration is difficult and the relative movement of the structure is very large. Dr. Cascio, in collaboration with Dr. Nagle, has been successful in recording longitudinal activation in an ischemic rabbit papillary muscle. This group has also presented data on activation of the iridium sites to reduce impedances to levels suitable for their recordings. Investigators from several disciplines have been pursuing methods to use probes for recording from tissue slices, including retina and salamandar olfactory bulb.